Well, I tried a Google search on the very topic. There are some pros and cons to various methods all over the internet. However, I learned somethings doing this search. The Bosch O2 sensors have the best chance of being cleaned without being damaged or ruined.
Solvent Pro: It does not exceed temp of 850 degrees burning off the carbon buildup. Get a solvent that drys clean with no residue. Works good on the wires and breather air-port of the O2 sensor.
Solvent Con: must not leave a residue and must be O2 sensor safe. It can get messy.
Torch Pro: cleans off the caked on mess for really messed up O2 sensors.
Torch Con: if the O2 sensor exceeds a high temp, it's ruined. Avoid melting the wires.
Since the other fourm topic was about gas mileage, I've tuned-up and even cleaned the IAC. The IAC got me from 10 to 11.7mpg, but the van is amiss of getting above 12 or more mpg like it should.
Much thanks goes out to the people at the BMW and Volvo forums for some detailed information on how to clean the O2 sensor.
I guess the price they pay for a new sensor is worth trying to clean the one they got first.
The first thing learned was, NEVER use any alcohol on the sensor. PERIOD.
Another thing was, NEVER use any anti-seize compond on the threads to re-install or install a new on since the sensor is chemical reaction based. The anti-seize compond will mess up (foul) the sensor.
The sensors have a "fresh-air" tube or port to them that sample the air and compares the exhaust gases. In some instances, if the port becomes clogged or dirty, the O2 sensor doesn't report a fault to the computer OBD system. The port is an open port on the sensor or the port is the tubing of the wire connector.
But before I state anything though, take this information at your own risk.
After doing research for cleaning O2 sensors, it seems that many of the other forums, from american cars to jap cars and even a audi/benz forums have found some solutions to clean the O2 sensors. Everyone seems to use CRC brand "QD electronic cleaner" for both O2 sensors and airflow sensors. it is a special cleaner that has NO RESIDUE in it so when it dries it dries 100% clean with no oils or etc as if it were brand new. For the airflow sensors they sprayed it from a safe distance (as far away as possible) in order to be careful b/c of the sensitive electronics (you don't want to powerblast the sensor close range). The O2 sensor they sprayed the outsides and insides with the same cleaner and saw great results: better gas mileage, better running car, all check engine / warning lights went away.
I see a lot of people on this forum replacing O2 sensors which can get very expensive. After reading up on these issues on other forums i have read horror stories where people replaced hundreds of $ worth of parts and when they cleaned the O2 sensor all their problems went away. One forum member said he has been using the same O2 sensor for over 6 years jus t simply cleaning it over and over again (as long as electrical components are still intact then it should continue to work).
I just thought i'd share this information with you guys so we don't keep have to replacing these expensive components. Again use this information at your own risk but for those of you who already have failing O2 sensors it might be worth it to give it a shot and see what the results are b/c you have nothing to lose, it worked for others so it may work for you as well.
inside is a chemical generator and a comparaitor of sorts. anti-sieze can't be burned off, so that is what would lead to the death of the sensor. It wouldn't be able to get anything in to read. You also have to be careful of where the O2 sensor gets its outside air supply for comparaison. If a hole on the outside (old school) then make sure that stays clean. If through the wire harness, then don't use any goop on the harness plug side of things. make sure the tube holder and cover area is clean as well.
Its the bits inside the O2 sensor that need to be clean of contaminants. Usually if the O2 heater is broken or the car is just really sooty with the exhaust, you can get a lot of *stuff* packed into the O2 and it won't be able to get it all out. If the sensor is indeed still good, just cleaning that stuff out would fix the problem.
*Note: people have tried this method in the BMW forums. Some with great success while others with mild improvements. One person reported no benefit at all.
What will damage my O2 sensor?
Home or professional auto repairs that have used silicone gasket
sealer that is not specifically labeled "Oxygen sensor safe",
"Sensor safe", or something similar, if used in an area that
is connected to the crankcase. This includes valve covers, oil
pan, or nearly any other gasket or seal that controls engine oil.
Leaded fuel will ruin the O2 sensor in a short time. If a car is
running rich over a long period, the sensor may become plugged up
or even destroyed. Just shorting out the sensor output wire will
not usually hurt the sensor. This simply grounds the output
voltage to zero. Once the wiring is repaired, the circuit
operates normally. Undercoating, antifreeze or oil on the
*outside* surface of the sensor can kill it. See how does an
Oxygen sensor work.
Here's some technical reading of the O2 sensor in laymen terms. http://www.kemparts.com/TechTalk/tt07.asp
A Ford Mustang technical website states this.
To check the sensors first disconnect and inspect the wiring, remove the sensors and clean them, don't use any type of chemicals to do this, the cleaning should be done by using a PROPANE TORCH, place the sensor tip inside the propane flame for a few seconds at a time until all contaminants get evaporated by the heat. Place the sensors back in place.
This seemed helpful to know that the fresh air part of the O2 sensor can get blocked or clogged.
If the sensor is blocked somehow, or it cannot heat up to complete the loop, the engine will begin to suffer from lousy fuel mileage, high emissions and weak power. Sometimes the exterior of the Chrysler oxygen sensor will become blocked with engine fluids, such as coolant, oil and corrosion. If cleaning your Chrysler oxygen sensors does not alleviate any problems, it is time to order a new set from our site and replace them.
Some things to note about O2 sensors that can damage them.
- The sensor contains a ceramic module and should not be subject to mechanical or thermal shock or it may be damaged. Thermal shock would occur if liquid drops of water were to contact the sensor.
- The sensor is not designed for operation on leaded fuels, doing so will shorten sensor life.
- Long term running in the rich region will shorten sensor life, running very rich will dramatically reduce sensor life.
- High exhaust temperatures (over 850 deg C, 1560 deg F) will shorten sensor life.
- Engine oil consumption at a rate greater than 1 quart per1,000 miles will shorten sensor life.
- It may be possible to "clean" sensors. This must be done before the sensor has completely failed.
- A good rule of thumb for sensor life is: A sensor will last about as long as your spark plugs. If your spark plugs are fouled by lead or very rich running, you sensor is likely to have failed also.
From the Toyota forums
Has anyone done this and had positive results?
Did you use throttle body cleaner?
Any points to give on the procedure? I'll check my Haynes manual for removal/installation.
I don't have a code or anything. I just thought that after the Seafoam treatment I'd make sure everything was as clean as possible (for being in an exhaust pipe).
I've done this a few times on my '85 4Runner 22re while messing with getting the TPS set correctly. I used a throttle body cleaner that specifically stated that it was safe for o2 sensors. I just pull the o2, hold it over a rag, put the tube into the body and start washing it out tapping it every so often to knock out hunks and gunk. You might be surprised how much comes out! It has been many months since I first did this and I haven't had any issues so far.
Past that.. I've had mixed results cleaning 'em, mostly good though, which means that I've gotten more life than normal out of them. And yes, TB cleaner would be the right thing to use.
Did you notice any change in MPG with cleaning the O2 sensor?
Yes, for the better. But it's more about the ECU being able to get a better read on what's going on. That will affect your mileage numbers, but also performance.
When you do this, it is a good time to pull the EFI fuse or the negative cable on your battery. I do the cable since I don't even have so much as a stereo in my old dog so I don't need to worry about losing any presets.
This will allow the ECU to reset and relearn from the new readings from the clean o2. It will definitely effect fuel economy IMO since if it is dirty it should tend to read lean which in turn will make the ECU crank up the fuel rate, which gets more carbon building up on the o2, which should result in the o2 reporting lean conditions, which makes the ECU crank up the fuel rate...you see how it can start spiralling downwards.
Cleaning the O2 sensor can be hit & miss. It's not a part that is _supposed_ to be able to handle solvents. The elements inside that react with the exhaust gases (and end up producing the voltage that the ECU needs) can become brittle. Throwing a solvent on them can hasten that process.
You'll know more about your results in this tankfull. If things turn out "bad", then as you spend the $90/$140, remember that you were on borrowed time anyway.